Baxi105he with thermostatic shower problems

[Cassius01]

Hi all,
I've stumbled across this website while searching for an answer and it looks a great place to start,
Basically my thermostatic shower temperature was fluctuating, I narrowed this down to being the boiler cutting off for around ten seconds every minute or so!
My gut feeling was the cartridge in the shower was asking for less hot water which was causing the boiler to cut off due to insufficient pressure! I changed the diaphragm which I thought would fix this which it hasn't!!
Does anybody got any suggestions as to what this could be?

Cheers in advance
Matt

 

[gas112]

If its only showing on the shower and taps seem ok then its the venturi assy in the righthand brass section of boiler where the 2 little brass tubes from diaphragm housing go to .
They are made of plastic and fall apart starting to show up on a lot of the HE`s now and as said shows up on shower majority of time.

If you watch the pin from diaphragm whilst shower is on you will see it comes back off the microswitch as shower gets hot then as it cools it moves back onto microswitch

 

[Cassius01]

Thanks for the quick reply gas 112, do you mean the bit in the flow regulator? I'm looking in the book now trying to see which bit it is before I get the plumber back out, the hot pipe going into the shower valve goes cold when the shower goes cold so it seems like the shower is requesting less hot water and the boiler is sending cold? If that makes sense! Is the Venturi a part you can buy seperarly? Sorry for all the questions

 

[ianmcd]

The fault that Gas112 is referring to (and most likely the culprit) is inside your boiler and not your shower cartridge

 

[Cassius01]

Hi Ian,

Yea I thought it was in the boiler, looking at the manual the only mention of a Venturi was in the flow regulator so I was just checking we were talking about the same thing do you think it will be the same part? I've already changed the diaphragm and the plate heat exchanger!

Thanks
Matt

 

[ianmcd]

Hi Matt

Page 29 fig 44 on your boilers installation and servicing instructions shows you what you should be looking at

 

[Cassius01]

My page 29 only has fig 47 48 and 49??

 

[ianmcd]

page 36 fig 60 on this link

http://www.baximarketing.co.uk/discontinued-literature/combi-boilers/Baxi-Combi-105-install.pdf

 

[Cassius01]

Cheers that's the bit I was looking at in my book is it an easy to get part ?

 

[ianmcd]

http://www.ebay.co.uk/itm/Baxi-Comb...arden_Hearing_Cooling_Air&hash=item484738d42c

 

[gas112]

To change its a 5 min job or a half hour pain in the arse if it has completly fell apart and have to fish the bits out .
Water off 22mm RING spanner to remove it then split it from cartridge body .
13 QUID aint a bad price i pay 8 or 9 for them trade

 

[ianmcd]

well Gas112 at least I know where the thank you button is , was waiting on the OP asking me to buy the bloody thing and send it to them ha ha

 

[Cassius01]

Ha ha thanks ian and gas112, was just getting the kids to bed! I do appreciate the advise and I will let you know how I get on, just as a matter of interest I have a bath filler that runs off the same shower valve control and this doesn't go hot and cold?

 

[Cassius01]

Didn't even know there was a thank you button!

 

[gas112]

its cause when the shower thermostat reaches temp it restricts the flow of water through the boiler and because the venturi is not working correctly it stops the diaphragm getting correct pressures either side for it to move and operate the microswitch